+动词原形
与过去事实相反
had+过去分词
should would could +have+过去分词 might
与将来事实相反
① 过去式（be 通常 用were）
② should+动词原形 ③ were to+动词原形
should would could might
.
+动词原形
7
一、与现在事实相反
1. If I knew his telephone number, I would tell you .
A. wouldn’t die
B. didn’t dieC. hadn’t Nhomakorabeadied
D. wouldn’t have d. ied
13
5.Had I known about the computer program, a huge amount of time and energy_____.
A. would have been saved
.
5
If引导的虚拟条件句，即非真实条件句，表示条 件句所表示的条件根本不可能实现或实现的可 能性很小。根据动作发生时间的不同，含有非 真实条件句的复合句的主从句的谓语动词采用 不同的表达方式。具体分为三种情况：
.
6
时间
从句
主句
与现在事实相反
过去式 （be 通常用were）
should would could might
真实条件句和 虚拟条件句
.
1
.
2
1.表示客观事实或真理
If you freeze water, it turns to ice. If you eat a lot of chocolate, you put on weight.
从句
主句
if+一般现在时，一般现在时
.
3
2.表示将来可能发生的事 If he fails in the exam, he will let his parents down. You will certainly succeed if you keep on trying.
A. But for their care B. If they were careful C. Without their care D. If they had been more careful
.
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4.—The weather has been very hot and dry. —Yes. If it had rained even a drop, things would be much better now! And my vegetables____.
.
9
三、与将来的事实相反
1.If there were a heavy snow next Sunday, we would not go skating.
2.If she should come, I would tell her about the matter.
.
10
1. The printer is of good quality.
B. had been saved
C. will be saved
D. was saved
.
14
6.If we ____ the other road, we might have arrived here in time for the meeting.
A. take B. had taken C. took D. have taken
If it _____break down within
the first year , we would repair
it at our expense.
A. would
B. should
C. could
D. might
.
11
2._____,the forest fire would have been discovered much earlier.
从句
主句（陈述句）
if+一般现在时，一般将来时（will+动词原形）
.
4
3.给某人提建议或命令某人做某事 If you feel sleepy, go to bed. If you want to know how it works, read the
instructions.
从句
主句
if+一般现在时，祈使句
.
15
(2)单句改错
①He wouldn’t feel so cold if he was indoors. was→were
②If we had started earlier, we couldn’t had missed the
first bus. ③If he had time, he will come.
第二个had→have had→has
.
16
Thank you !
.
17
2. If I were you ,I wouldn't be so proud.
.
8
二、与过去事实相反
1.If he had taken my advice, he would not have made such a mistake.
2.If I had got there earlier, I would have met her.